3/4T Manac trailer tires

[chris vickery]

I have a 1981 Manac trailer ex-CF that is starting to show her age.
Used up my last decent spare tire as my original tires are getting pretty bad.
Wondering if anyone has a source for these tires or could offer up an option that might be more obtainable?
I understand that the CF spec’d these trailers to be towed behind a 5/4 pickup, hence the smaller truck type tires and rims as opposed to the regular 9.00-16s used on most M101 3/4 trailers.
I believe the rim size of 16.5 makes replacement tires difficult to find.
I would however love to find a set of originals if anyone had a set laying around?
Alternately, is there another rim that would swap straight or even a hub/rim replacement that would work?
Trying to be frugal as this trailer is used only as my GP trailer and I don’t have lots of dollars into it to begin with...